The properties of a glass material can be varied in desirable ways by appropriately selecting the components of the glass composition, and by varying the proportion of each component. For this reason, glass materials have been used in many different applications including electronics and optics.
However, depending on the composition, the material undergoes crystal precipitation or phase separation, which makes it difficult to vitrify the material uniformly. Further, some components do not melt even under high temperature, and remain as an unmelted solid. That is, there are many compositions that are difficult to vitrify with the use of a common method in which a batch of raw material is placed in a ceramic or platinum crucible and melted in a high-temperature furnace. Many other compositions are only usable to produce a powder or a flaky glass, and cannot produce a mass or a bulk glass more voluminous than a powder or a flaky glass. For example, titanium oxide (TiO2), known as a high refractive-index glass material (see, for example, Precision Molding Technology of Low-Melting and Free-lead Glass Outlined from Recent Japanese Patents (2), Materials Integration, Vol. 18, No. 10, (2005), p. 58-66), is expected to find applications in the field of optics. However, because titanium oxide easily crystallizes, it has been difficult to produce a bulk glass using titanium oxide as a main material. Attempts have been made to obtain glass by rapidly roller quenching a melt prepared from a mixture of titanium oxide and lanthanum oxide (La2O3). However, this method is only capable of producing a laminar glass, not a bulk glass.
There have been proposed methods of producing a single crystal piece or a ceramic of barium-titanium oxide, in which the barium-titanium oxide is melted and solidified in the levitation state (levitation method; see JP2005-53726A, and JP2005-213083A).